[Illustration: 11-INCH SUTTON TRENCH MORTAR.] The plan was adopted of building these shell of lap-welded, 3-inch steel tubing, cut into proper lengths. The contracts for the finished machined and assembled shell were placed with the General Motors Corporation at its Saginaw (Mich.) plant, with H. C. Dodge (Inc.), at South Boston, Mass., and with the Metropolitan Engineering Co., of Brooklyn, N. Y. In order to facilitate production, the Government agreed to furnish the steel tubing. For this purpose it ordered from the National Tube Co., of Pittsburgh, Pa., 1,618,929 pieces of steel tubing, each 11 inches in length, and from the Allegheny Steel Co., at Brakenridge, Pa., 2,332,319 running feet of tubing. These tube contracts were filled by the early spring of 1918. The railroad congestion of February and March, 1918, held up the delivery of tubing, but the assembly plants utilized the time in tooling up for the future production. All the plants thereafter soon reached a quantity production, the General Motors Corporation in particular tuning up its shop system until it was able to reach a maximum daily production in a 10-hour shift of 35,618 completed shell. The casting of malleable iron bodies for the practice shell of this caliber was turned over to the Erie Malleable Iron Co., of Erie, Pa., and to the National Malleable Castings Co., with plants at Cleveland, Chicago, Indianapolis, and Toledo. The former concern cast 196,673 bodies and the latter 1,015,005. The Gorham Manufacturing Co., of Providence, R. I.; the Standard Parts Co., of Cleveland, Ohio; and the New Process Gear Corporation, of Syracuse, N. Y., machined and assembled the practice shell. When the armistice was declared, these three contracts were approximately seven-tenths complete. We were dissatisfied with our 3-inch shell, for the reason that they tumbled in air and were visible to the eye. The French had developed a mortar shell on the streamline principle which was invisible in flight and had twice the range of ours. Had the war continued the Trench Warfare Section would have produced streamline shell for mortars. The second mortar project undertaken was the manufacture of the 240-millimeter weapon. This was the largest mortar which we produced, its barrel having a diameter of approximately 10 inches. It proved to be one of the toughest nuts to crack in the whole mortar undertaking. The British designs of this French weapon we found to be quite unsuited to our factory methods, and for the sake of expediency we frequently modified them in the course of the development. The total contracts called for the production of 938 mortars.